As new objects begin to support new labels, start to generalize

the default label support in /etc/mac.conf.  Rather than maintain
each default label type in an explicit global variable in mac.c,
keep a list of defaults loaded from the configuration file.
Generalize the parsing so that we support both the older:

        default_file_labels foo
        default_ifnet_labels foo
        default_process_labels foo

And also a new:

        default_labels file foo
        default_labels ifnet foo
        default_labels process foo

We now accept arbitrary object classes in the first argument.  If
the same object is specified more than once, we discard the
earlier definition in favor of the later one.

Add a new API, mac_prepare_type(), which accepts a mac_t to
prepare, as well as an object name in the second argument, which
will pull a default label set for the object out of the
configuration loaded by mac_init_internal().  This permits the libc
to adapt to new objects known about by applications but not by libc
at compile-time.

Also liberalize the error handling a bit: if we're using implicit
initialization (i.e., the application didn't explicitly initialize
the MAC code), ignore syntax errors and only use valid lines.  In
the future, we may want to add explicit warnings and do this a
bit more consistently.

While here, add support for a MAC_CONFFILE environmental variable,
which may be used to specify an alternative mac.conf configuration
file if the application isn't running with modified privilege
(issetugid()).

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, Network Associates Laboratories

1 files changed, 192 insertions, 86 deletions

diff --git a/lib/libc/posix1e/mac.c b/lib/libc/posix1e/mac.c
index 3c08e47..3426ac3 100644
--- a/lib/libc/posix1e/mac.c
+++ b/lib/libc/posix1e/mac.c
@@ -1,6 +1,6 @@
 /*
  * Copyright (c) 1999, 2000, 2001, 2002 Robert N. M. Watson
- * Copyright (c) 2002 Networks Associates Technology, Inc.
+ * Copyright (c) 2002, 2003 Networks Associates Technology, Inc.
  * All rights reserved.
  *
  * This software was developed by Robert Watson for the TrustedBSD Project.
@@ -49,28 +49,29 @@
 
 static int	internal_initialized;
 
-/* Default sets of labels for various query operations. */
-static char	*default_file_labels;
-static char	*default_ifnet_labels;
-static char	*default_process_labels;
+/*
+ * Maintain a list of default label preparations for various object
+ * types.  Each name will appear only once in the list.
+ *
+ * XXXMAC: Not thread-safe.
+ */
+LIST_HEAD(, label_default) label_default_head;
+struct label_default {
+	char				*ld_name;
+	char				*ld_labels;
+	LIST_ENTRY(label_default)	 ld_entries;
+};
 
 static void
 mac_destroy_labels(void)
 {
+	struct label_default *ld;
 
-	if (default_file_labels != NULL) {
-		free(default_file_labels);
-		default_file_labels = NULL;
-	}
-
-	if (default_ifnet_labels != NULL) {
-		free(default_ifnet_labels);
-		default_ifnet_labels = NULL;
-	}
-
-	if (default_process_labels != NULL) {
-		free(default_process_labels);
-		default_process_labels = NULL;
+	while ((ld = LIST_FIRST(&label_default_head))) {
+		free(ld->ld_name);
+		free(ld->ld_labels);
+		LIST_REMOVE(ld, ld_entries);
+		free(ld);
 	}
 }
 
@@ -84,88 +85,175 @@ mac_destroy_internal(void)
 }
 
 static int
-mac_init_internal(void)
+mac_add_type(const char *name, const char *labels)
 {
-	FILE *file;
+	struct label_default *ld, *ld_new;
+	char *name_dup, *labels_dup;
+
+	/*
+	 * Speculatively allocate all the memory now to avoid allocating
+	 * later when we will someday hold a mutex.
+	 */
+	name_dup = strdup(name);
+	if (name_dup == NULL) {
+		errno = ENOMEM;
+		return (-1);
+	}
+	labels_dup = strdup(labels);
+	if (labels_dup == NULL) {
+		free(name_dup);
+		errno = ENOMEM;
+		return (-1);
+	}
+	ld_new = malloc(sizeof(*ld));
+	if (ld_new == NULL) {
+		free(name_dup);
+		free(labels_dup);
+		errno = ENOMEM;
+		return (-1);
+	}
+
+	/*
+	 * If the type is already present, replace the current entry
+	 * rather than add a new instance.
+	 */
+	for (ld = LIST_FIRST(&label_default_head); ld != NULL;
+	    ld = LIST_NEXT(ld, ld_entries)) {
+		if (strcmp(name, ld->ld_name) == 0)
+			break;
+	}
+
+	if (ld != NULL) {
+		free(ld->ld_labels);
+		ld->ld_labels = labels_dup;
+		labels_dup = NULL;
+	} else {
+		ld = ld_new;
+		ld->ld_name = name_dup;
+		ld->ld_labels = labels_dup;
+
+		ld_new = NULL;
+		name_dup = NULL;
+		labels_dup = NULL;
+
+		LIST_INSERT_HEAD(&label_default_head, ld, ld_entries);
+	}
+
+	if (name_dup != NULL)
+		free(name_dup);
+	if (labels_dup != NULL)
+		free(labels_dup);
+	if (ld_new != NULL)
+		free(ld_new);
+
+	return (0);
+}
+
+static char *
+next_token(char **string)
+{
+	char *token;
+
+	token = strsep(string, " \t");
+	while (token != NULL && *token == '\0')
+		token = strsep(string, " \t");
+
+	return (token);
+}
+
+static int
+mac_init_internal(int ignore_errors)
+{
+	const char *filename;
 	char line[LINE_MAX];
+	FILE *file;
 	int error;
 
 	error = 0;
 
-	file = fopen(MAC_CONFFILE, "r");
+	LIST_INIT(&label_default_head);
+
+	if (!issetugid() && getenv("MAC_CONFFILE") != NULL)
+		filename = getenv("MAC_CONFFILE");
+	else
+		filename = MAC_CONFFILE;
+	file = fopen(filename, "r");
 	if (file == NULL)
 		return (0);
 
 	while (fgets(line, LINE_MAX, file)) {
-		char *arg, *parse, *statement;
+		char *arg, *comment, *parse, *statement;
 
 		if (line[strlen(line)-1] == '\n')
 			line[strlen(line)-1] = '\0';
 		else {
+			if (ignore_errors)
+				continue;
 			fclose(file);
 			error = EINVAL;
 			goto just_return;
 		}
 
-		parse = line;
-		statement = "";
-		while (parse && statement[0] == '\0')
-			statement = strsep(&parse, " \t");
-
-		/* Blank lines ok. */
-		if (strlen(statement) == 0)
-			continue;
+		/* Remove any comment. */
+		comment = line;
+		parse = strsep(&comment, "#");
 
-		/* Lines that consist only of comments ok. */
-		if (statement[0] == '#')
+		/* Blank lines OK. */
+		statement = next_token(&parse);
+		if (statement == NULL)
 			continue;
 
-		if (strcmp(statement, "default_file_labels") == 0) {
-			if (default_file_labels != NULL) {
-				free(default_file_labels);
-				default_file_labels = NULL;
+		if (strcmp(statement, "default_labels") == 0) {
+			char *name, *labels;
+
+			name = next_token(&parse);
+			labels = next_token(&parse);
+			if (name == NULL || labels == NULL ||
+			    next_token(&parse) != NULL) {
+				if (ignore_errors)
+					continue;
+				error = EINVAL;
+				fclose(file);
+				goto just_return;
 			}
 
-			arg = strsep(&parse, "# \t");
-			if (arg != NULL && arg[0] != '\0') {
-				default_file_labels = strdup(arg);
-				if (default_file_labels == NULL) {
-					error = ENOMEM;
-					fclose(file);
-					goto just_return;
-				}
+			if (mac_add_type(name, labels) == -1) {
+				if (ignore_errors)
+					continue;
+				fclose(file);
+				goto just_return;
 			}
-		} else if (strcmp(statement, "default_ifnet_labels") == 0) {
-			if (default_ifnet_labels != NULL) {
-				free(default_ifnet_labels);
-				default_ifnet_labels = NULL;
+		} else if (strcmp(statement, "default_ifnet_labels") == 0 ||
+		    strcmp(statement, "default_file_labels") == 0 ||
+		    strcmp(statement, "default_process_labels") == 0) {
+			char *labels, *type;
+
+			if (strcmp(statement, "default_ifnet_labels") == 0)
+				type = "ifnet";
+			else if (strcmp(statement, "default_file_labels") == 0)
+				type = "file";
+			else if (strcmp(statement, "default_process_labels") ==
+			    0)
+				type = "process";
+
+			labels = next_token(&parse);
+			if (labels == NULL || next_token(&parse) != NULL) {
+				if (ignore_errors)
+					continue;
+				error = EINVAL;
+				fclose(file);
+				goto just_return;
 			}
 
-			arg = strsep(&parse, "# \t");
-			if (arg != NULL && arg[0] != '\0') {
-				default_ifnet_labels = strdup(arg);
-				if (default_ifnet_labels == NULL) {
-					error = ENOMEM;
-					fclose(file);
-					goto just_return;
-				}
-			}
-		} else if (strcmp(statement, "default_process_labels") == 0) {
-			if (default_process_labels != NULL) {
-				free(default_process_labels);
-				default_process_labels = NULL;
-			}
-
-			arg = strsep(&parse, "# \t");
-			if (arg != NULL && arg[0] != '\0') {
-				default_process_labels = strdup(arg);
-				if (default_process_labels == NULL) {
-					error = ENOMEM;
-					fclose(file);
-					goto just_return;
-				}
+			if (mac_add_type(type, labels) == -1) {
+				if (ignore_errors)
+					continue;
+				fclose(file);
+				goto just_return;
 			}
 		} else {
+			if (ignore_errors)
+				continue;
 			fclose(file);
 			error = EINVAL;
 			goto just_return;
@@ -187,7 +275,7 @@ mac_maybe_init_internal(void)
 {
 
 	if (!internal_initialized)
-		return (mac_init_internal());
+		return (mac_init_internal(1));
 	else
 		return (0);
 }
@@ -198,7 +286,7 @@ mac_reload(void)
 
 	if (internal_initialized)
 		mac_destroy_internal();
-	return (mac_init_internal());
+	return (mac_init_internal(0));
 }
 
 int
@@ -267,7 +355,21 @@ mac_prepare(struct mac **mac, char *elements)
 }
 
 int
-mac_prepare_file_label(struct mac **mac)
+mac_prepare_type(struct mac **mac, const char *name)
+{
+	struct label_default *ld;
+
+	for (ld = LIST_FIRST(&label_default_head); ld != NULL;
+	    ld = LIST_NEXT(ld, ld_entries)) {
+		if (strcmp(name, ld->ld_name) == 0)
+			return (mac_prepare(mac, ld->ld_labels));
+	}
+
+	return (ENOENT);		/* XXXMAC: ENOLABEL */
+}
+
+int
+mac_prepare_ifnet_label(struct mac **mac)
 {
 	int error;
 
@@ -275,14 +377,11 @@ mac_prepare_file_label(struct mac **mac)
 	if (error != 0)
 		return (error);
 
-	if (default_file_labels == NULL)
-		return (mac_prepare(mac, ""));
-
-	return (mac_prepare(mac, default_file_labels));
+	return (mac_prepare_type(mac, "ifnet"));
 }
 
 int
-mac_prepare_ifnet_label(struct mac **mac)
+mac_prepare_file_label(struct mac **mac)
 {
 	int error;
 
@@ -290,11 +389,21 @@ mac_prepare_ifnet_label(struct mac **mac)
 	if (error != 0)
 		return (error);
 
-	if (default_ifnet_labels == NULL)
-		return (mac_prepare(mac, ""));
+	return (mac_prepare_type(mac, "file"));
+}
 
-	return (mac_prepare(mac, default_ifnet_labels));
+int
+mac_prepare_packet_label(struct mac **mac)
+{
+	int error;
+
+	error = mac_maybe_init_internal();
+	if (error != 0)
+		return (error);
+
+	return (mac_prepare_type(mac, "packet"));
 }
+
 int
 mac_prepare_process_label(struct mac **mac)
 {
@@ -304,10 +413,7 @@ mac_prepare_process_label(struct mac **mac)
 	if (error != 0)
 		return (error);
 
-	if (default_process_labels == NULL)
-		return (mac_prepare(mac, ""));
-
-	return (mac_prepare(mac, default_process_labels));
+	return (mac_prepare_type(mac, "process"));
 }
 
 /*